KR101884196B1 - Method of inspecting denting trace of anisotropic film - Google Patents

Abstract

The present invention relates to a method to inspect a denting trace in attachment of a conductive film and, more specifically, to a method to inspect whether a state of a conductive particle, which is generated in a stop of attaching an anisotropic conductive film (ACF) on an electrode of a substrate, disposing a film or an flexible printed circuit (FPC) on the ACF, and allowing the FPC and the electrode of the substrate to be in contact with each other so as to be electrically connected, included in an anisotropic conductive film (ACF) is bad. To this end, according to the present invention, the method to inspect a denting trace in attachment of a conductive film comprises: a step (S100) of setting a denting trace inspection area; a step (S110) of varying a lighting angle to set the lighting angle relatively clearly showing a denting trace and photographing a panel image by an optical camera; a step (S120) of setting an enlargement area to the set inspection area; a step (S130) of recognizing a rotational angle and a complete lead in the area through frequency and histogram analysis; a step (S140) of digital-imaging the denting trace through denting trace model filtering; a step (S150) of removing the denting trace out of set minimum and maximum sizes as noise; a step (S160) of schematizing the denting trace and clustering a plurality of denting traces of a set size within a set distance; a step (S170) of counting the number of denting traces and the length of a denting trace distribution by each lead; and a step (S180) of determining defect of the denting trace based on a set criterion.

Description

TECHNICAL FIELD [0001] The present invention relates to an inspecting denting trace of anisotropic film,

The present invention relates to a method of inspecting an indentation state when a conductive film is adhered, and more particularly, to a method of inspecting an indentation state when a conductive film is adhered, and more particularly to a method of inspecting an indentation state when an anisotropic conductive film (ACF) And a method for inspecting whether or not a state of a conductive particle in an ACF generated in a step in which an FPC and an electrode of a substrate are brought into contact with each other is conducted.

2. Description of the Related Art Generally, an electronic apparatus such as a mobile phone, a mobile terminal, or a liquid crystal TV is provided with an LCD panel (hereinafter referred to as a " substrate "). Such a substrate is typically mounted on a substrate by a FOG (Film On Glass) / FOP (Film On Panel) method or a COG (Chip On Glass) / COP (Chip On Panel) method.

That is, in the FOG / FOP bonding method, an anisotropic conductive film (hereinafter referred to as ACF) is usually attached to an electronic circuit electrode printed on a glass or plastic substrate, a film or an FPC is disposed on the ACF, And the electrodes of the FPC and the substrate are brought into contact with each other.

At this time, the ACF contains conductive particles, and when a certain pressure is applied, the insulating film is broken and electricity can be applied through the conductive particles.

In the COG / COP bonding method, an anisotropic conductive film is usually attached to an electrode of a substrate, a semiconductor chip is disposed on the ACF, and an appropriate pressure is applied to the bump, to be.

 Thus, in the process of connecting an FPC or a chip to a substrate through the COG / COP and FOG / FOP processes, the attachment state of the ACF is a very important factor.

That is, the degree of breakage of the conductive particles in the ACF is a factor greatly affecting the determination of whether or not the product is defective.

Therefore, after the ACF is attached to the electrode of the substrate, it is essential that the foreign substance state, mounting position, indentation state (number of indentations of ACF conductive particles, indentation strength, indentation length, indentation distribution) to be.

At this time, there is a need for a method of judging whether or not there is a defect by calculating the number, strength, length, and distribution of conductive particles in each bump by analyzing the image information, to be.

Conventionally, the apparatus for high-speed image capturing due to the development of peripheral technology has been satisfied in the conventional inspection apparatus, but it has a problem that the technique of noise and clustering of the conductive particles is not easily obtained by drawing it based on the photographed image.

 As a result, the defective material is transferred to the next process due to a failure to determine whether the adhesion of the conductive particles is poor or not, thereby causing damage to the process and increasing the possibility of production of defective products. .

Korean Patent Publication No. 10-0976802 Korean Patent Publication No. 10-0766394

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems as described above, and it is an object of the present invention to provide a method and apparatus for visualizing a video image photographed by an optical camera, The noise reduction, clustering, and the size and quantity of the particles per lead are counted to provide an indentation inspection method capable of accurately determining whether or not a defect is relatively large with respect to time, .

Other objects and advantages of the present invention will be described hereinafter and will be understood by the embodiments of the present invention. Further, the objects and advantages of the present invention can be realized by the means and the combination shown in the claims.

According to another aspect of the present invention, there is provided a method of inspecting an indentation state when a conductive film is attached, comprising the steps of: setting an indentation inspection region (S100); A step S110 of changing the illumination angle to set an illumination angle in which the indentation is clearly visible, and photographing the panel image by the optical camera; Setting an enlarged area to the set inspection area (S120); Recognizing a complete lead within a rotation angle and a region through frequency and histogram analysis (S130); (S140) binarizing the indentation through indentation model filtering; Removing (S150) indentations that deviate from the set minimum and maximum and outliers as noise; (S160) clustering a plurality of indentations of a set size into a single set within a set distance; (S170) counting the number of indentations and indentation distribution length per lead; Determining whether the indentation is defective according to the setting reference (S180); And a method of inspecting an indentation state when the conductive film is attached.

As described above, according to the present invention, it is possible to precisely inspect an object to be inspected by providing an inspection speed at which a full inspection can be performed by the indentation state inspection method when the conductive film is attached, The defective material is transferred to the next process, which not only damages the process but also increases the possibility of production of the defective product, thereby solving the problem of reducing the stability of the product.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart of a method for examining an indentation state when a conductive film is attached according to the present invention. FIG.
2 is an original panel image taken by an optical camera according to the present invention.
FIG. 3 is a diagram illustrating a step of setting an enlarged area to a set inspection area according to the present invention. FIG.
FIG. 4 is a diagram illustrating a Discrete Fourier Transform (DFT) for transforming an image according to the present invention into a frequency domain. FIG.
5 is a view showing an image obtained by reversing the rotation angle of the lead according to the present invention.
FIG. 6 is an image diagram showing an image profile in which a lead image performed according to the present invention is projected in a vertical direction; FIG.
7 is a diagram illustrating a step of generating a reference mask by generalizing an indentation to extract an indentation having a predetermined inspection sensitivity or more according to the present invention.
FIG. 8 is a view illustrating an image obtained by filtering an image according to an exemplary embodiment of the present invention in units of regions and amplifying the indentation characteristics so as to be well displayed.
9 is a diagram showing a binary image according to the present invention.
FIGS. 10A and 10B are views showing a result of post-processing according to the present invention; FIG.
11 is a view showing a step of displaying the quantity of indentation and the length of indentation distribution by leads according to the present invention.

Before describing in detail several embodiments of the invention, it will be appreciated that the application is not limited to the details of construction and arrangement of components set forth in the following detailed description or illustrated in the drawings. The invention may be embodied and carried out in other embodiments and carried out in various ways. It should also be noted that the device or element orientation (e.g., "front," "back," "up," "down," "top," "bottom, Expressions and predicates used herein for terms such as "left," " right, "" lateral, " and the like are used merely to simplify the description of the present invention, Or that the element has to have a particular orientation. Also, terms such as " first "and" second "are used herein for the purpose of the description and the appended claims, and are not intended to indicate or imply their relative importance or purpose.

The present invention has the following features in order to achieve the above object.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

The indentation state inspection method when the conductive film is attached according to the present invention

(1) setting an indentation inspection area (S100)

(2) changing an illumination angle, setting an illumination angle in which an indentation is relatively clearly visible, and photographing a panel image by an optical camera (S110)

(3) setting an enlarged area to the set inspection area (S120)

(4) recognizing a complete lead in the rotation angle and the area through frequency and histogram analysis (S130);

(5) binarizing the indentation through indentation model filtering (S140);

(6) removing, as noise, indentations that deviate from the set minimum and maximum magnitudes (S150);

(7) Schematizing indentations and clustering multiple indents of a set size into one within a set distance (S160);

(8) counting the quantity and indentation distribution length of indentations per lead (S170);

(9) determining whether the indentation is defective according to the setting reference (S180);

The present invention also relates to a method of inspecting an indentation state at the time of attaching a conductive film.

In addition, in step S140, a step S140-1 of extracting an indentation having a predetermined inspection sensitivity or more is added to filter the indentation model, which is a step of setting the detection sensitivity in detecting the indentation, A step of lighter or darker representation on the image; .

In order to automatically recognize each lead, the pixel profile analysis using the vertical projection technique is performed. In order to apply the technique, in order to recognize the leads, the slopes of the leads are vertically parallel In order to do this, it is necessary to convert the image into the frequency domain in advance.

The frequency analysis is a step of performing image discrete Fourier transform (DFT) in order to convert an image into a frequency domain,

In the histogram analysis, the lead image is projected in the vertical direction to secure the image profile. In the image profile, the highest point and the lowest point are the boundaries of the respective leads, and the lead lengths shorter than the set points are incomplete leads, And preparing indentations for each lead to be extracted.

Also, in step S140,

      The shadow of the indentation is generated through the oblique light, and the upper semicircle is bright and the lower semicircle is dark in the shape of the indentation circle. Each indentation image is filtered by unit area to amplify the characteristic so that the characteristic is clearly visible. To the original image.

Also, in step S150,

Removing indentations that are less than the minimum indentation size and out of the maximum ideal size among the indentations displayed by the binarized image as noise.

Also, in step S160,

       And clustering the number of detected indentations within a predetermined size within a predetermined distance by counting the indentations as one indentation.

Also, in step S170,

Extracting whether or not the number of conductive balls is less than or equal to the set length of each lead; .

In addition,

A step (S100-1) of automatically setting a video image pickup area in advance or

(S100-2) of manually setting a necessary part as a video image capturing area.

 Hereinafter, Figs. 1 to 11 will be described in detail according to a preferred embodiment of the present invention.

(1) setting an indentation inspection area (S100)

 The indentation inspection area may be different depending on the inspection object. In general, the reference mark used for aligning the inspection object to the imaging area of the optical camera designates the left and right end areas of the printed inspection object, And a central area between the left and right sides is additionally set to prepare for photographing.

(2) photographing the panel image by the optical camera (S110)

As shown in FIG. 2, the inspection object is moved in accordance with the motor position value previously set based on the size of the inspected object and the reference mark position information, illumination is generated through the optical device for indentation inspection, Wherein the optimal illumination angle is set while varying the illumination angle of the optical device so that the indentation can be more clearly seen in the image.

(3) setting an enlarged area of the set inspection area (S120)

As shown in FIG. 3, the photographed inspection region may include an alignment mark, a margin of the inspection target, and unnecessary margins on the photographed image, which are not utilized for the indentation inspection. Therefore, to be. At this stage, the inspection area can be semi-automatic or manually lead.

(4) recognizing a complete lead in the rotation angle and the area through frequency and histogram analysis (S130);

In order to automatically recognize each lead, a pixel profile analysis using a vertical projection technique is performed. In order to apply this technique, the graded leads should be rotationally aligned so as to be vertically parallel to each other. (DFT) to transform the image into the frequency domain, as shown in FIG. 4, in order to convert the image into the frequency domain.

As shown in FIG. 5, after the rotation angle of the lead is determined, the image is rotated inversely, and then the performed lead image is projected in the vertical direction to secure an image profile, as shown in FIG.

In the image profile, the highest and lowest points will be the boundaries of each lead. This information is used to automatically recognize leads and prepare indentations for each lead.

If the projection accumulation value of the lead pixel is insufficient on the profile, it is determined that the sloped lead is an incomplete lead that occurs in the structure of designating a rectangular inspection area and excluded from the inspection object. In one embodiment, Is relatively shorter than the other lead lengths in the central portion, it is judged to be an incomplete lead and is excluded from the inspection board.

(5) binarizing the indentation through indentation model filtering (S140);

6, an incomplete lead is excluded, and indentation is extracted as an enlarged image of one indentation among the plurality of indentations represented on the lead, as shown in FIG. 7, based on the selected lead. For example, in the shape of a circle of indentation, a mask having information that the upper semicircle is bright and the lower semicircle is dark is designed by using an oblique light illuminated by the optical device to generate a shadow on the indentation, As shown in FIG. 8, the image is filtered by unit areas and amplified so that the characteristics are clearly displayed

As shown in FIG. 9, the step of removing the indentation region of the set size or smaller through the binarization process and extracting only the indentation region larger than the set size and rendering the extracted indentation region into the original image. In one embodiment, The point is indentation, and a white point of a predetermined size or more is extracted with respect to the white point.

In step S140, a step S140-1 of extracting indentations having a predetermined inspection sensitivity or more is added to the indentation model filtering. This step is to set the detection sensitivity in detecting the indentation, Lt; RTI ID = 0.0 > lighter < / RTI > .

As shown in FIG. 7, in the step of detecting the indentation, the detection sensitivity may be set to be lighter or darker on the image depending on the degree of depression of the conductive ball, and the region of the conductive ball may be determined to be indentation In one embodiment, the sensitivity of the test method is divided into 10 steps, and indentations can be detected or detected more according to the set step.

(6) removing, as noise, indentations that deviate from the set minimum and maximum magnitudes (S150);

In operation S150,

Removing indentations that are less than the minimum indentation size and out of the maximum ideal size among the indentations displayed by the binarized image as noise.

The step of removing indentations that are less than the minimum and maximum sizes out of the information of the detected indentations, considering the size or the area information, as noise, and in one embodiment, less than 25 pixels Or indentations exceeding 250 pixels are determined to be noise.

 The reason for the set value may be based on the actual size information of the conductive balls generating the indentations, but the small and large indentations are generated depending on the degree of crushing and the crowded state of the conductive balls in the randomly spreading ACF, And the set value is set as a reference.

 (7) Schematizing indentations and clustering multiple indents of a set size into one within a set distance (S160);

As shown in the post-processing result image of FIG. 10A, the indentation is schematized and the indentation detection post-processing step is carried out in such a manner that when the conductive ball is pressed or broken by a specific temperature and pressure in the process, When a plurality of detected indentations within a predetermined size are located within a predetermined distance, the counting by one indent is called clustering, as shown in FIG. 10B,

This is the step that includes the previous contents. Clustering criterion values are basically based on the size of the conductive balls, and experimental and numerical values may be set because there may be differences in the sample and the process.

(8) counting the quantity and indentation distribution length of indentations per lead (S170);

As shown in FIG. 11, the quantity and distribution length of the indentations may vary according to the density of the conductive display balls in the inspection display device and the ACF coated thereon. In one embodiment, If the number of balls is set to 10 or more per lead and the distribution length, which is a criterion for judging whether the conductive balls are not spread evenly over a limited lead area, is set to 200 μm, And extracting the data so that the rejection process can be performed.

Unlike the indentation shown in FIG. 11, the indentations at the lowest point and the highest point of the lead are represented by green, and the distance between the indentations is calculated to determine the distribution length.

(9) determining whether the indentation is defective according to the setting reference (S180);

Determining whether the indentation of the inspected object is good or bad according to a predetermined inspection standard on the basis of the number of indentations and the distribution length of each lead extracted at the previous step, and classifying whether to use or not to produce the product; .

Or setting the indentation inspection area (S100)

A step (S100-1) of automatically setting a video image pickup area in advance or

(S100-2) of manually setting a necessary part as a video image capturing area.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is to be understood that various changes and modifications may be made without departing from the scope of the appended claims.

Claims (8)

In the indentation state inspection method when a conductive film is attached,
A step of setting an indentation inspection area (S100)
A step S110 of changing the illumination angle to set an illumination angle in which the indentation is clearly visible and photographing the panel image by the optical camera,
Setting an enlarged area to the set inspection area (S120)
Recognizing a complete lead within a rotation angle and a region through frequency and histogram analysis (S130);
(S140) binarizing the indentation through indentation model filtering;
Removing (S150) indentations that deviate from the set minimum and maximum and outliers as noise;
(S160) clustering a plurality of indentations of a set size into a single set within a set distance;
(S170) counting the number of indentations and indentation distribution length per lead;
(S180) of determining whether the indentation is defective according to the setting reference,
In step S140, a step S140-1 of extracting an indentation having a predetermined inspection sensitivity or more is added to the indentation model filtering. This is a step of setting the detection sensitivity in detecting the indentation, And a step of expressing it lighter or deeper,
In step S130, a pixel profile analysis using a vertical projection technique is performed to automatically recognize each lead. In order to apply this technique, the leads having a slope are rotationally aligned so as to be vertically parallel And converting the image into a frequency domain in advance for this purpose,
The frequency analysis is a step of performing image discrete Fourier transform (DFT) in order to convert an image into a frequency domain,
In the histogram analysis, the lead image is projected in the vertical direction to secure the image profile. In the image profile, the highest point and the lowest point are the boundaries of the respective leads, and the lead lengths shorter than the set points are incomplete leads, Preparing lead indentations so that they can be extracted,
In step S140, shadows are generated on the indentations through the inclined light. In the shape of the indentations, the upper semicircle is bright and the lower semicircle is dark. Each indentation image is filtered by unit areas to amplify the characteristics And then visualizing the original image through a binarization imaging process,
In operation S150, the indentation that is less than the minimum indentation size and out of the maximum ideal size is regarded as noise among the indentations displayed by the binarized image,
The step of S160 may include clustering the indentation into a single indentation when the detected indentations within a predetermined size are located within a predetermined distance,
The step S170 includes extracting the number of conductive balls less than or equal to the set number based on the set length of each lead,
Wherein the step S100 includes automatically setting a video image pickup area in advance (S100-1) or manually setting a necessary part as a video image pickup area (S100-2). State inspection method.
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